Survival of Lactobacillus rhamnosus encapsulated with alginate and chitosan in simulated gastrointestinal conditions and during heat processing

In this study, chitosan-coated alginate beads were produced with different concentrations of chitosan and alginate to evaluate the survival of encapsulated Lactobacillus rhamnosus GG during exposure to adverse conditions in gastrointestinal simulated juice and heat processing. The encapsulation yield of different encapsulation treatments was between ۲۵ and ۵۳.۲%. Although there was a drastic decrease in pH within ۴۸ h of incubation in MRS medium inoculated with free and encapsulated bacteria, no significant changes (P > ۰.۰۵) in bacterial count were observed among different encapsulation treatments. Moreover, the survival rate after gastrointestinal juice exposure of all prepared beads was ۱۰–۸۷ times greater than that of free cells and was significantly enhanced by increasing chitosan and alginate concentrations. Theencapsulated bacteria survived significantly (P < ۰.۰۵) better than the free cells during heat exposure at ۵۵, ۶۰ and ۶۵ ◦ C: free cells experienced about ۵ log cycles reduction after heat treatment at ۶۵ ◦ C for ۳۰ min, whereas ۴۰ g L−۱ alginate/۱۰ g L−۱ chitosan-encapsulated L. rhamnosus was reduced by only ۲.۵۵ log cycles. CONCLUSION: Encapsulation effectively protected L. rhamnosus against heat treatment and gastrointestinal conditions, and this effect is important in delivering sufficient numbers of viable probiotic bacteria to the gastrointestinal tract.

Keywords:

Encapsulation , chitosan , alginate , gastrointestinal survival , acidifying ability , heat treatment , Lactobacillus rhamnosus.